To register an arrival in a Port, open the drawer for the given Port Call by clicking it in the list. Then click the icon at the top of the drawer and select "Register Arrival". A dialog will open and allow you to enter the arrival details.
The bunker categories listed here are only those that were used during the voyage.
If the registered date is in the past, the arrival date of the port call will be locked. Registered ROBs will also be locked as Arrival ROBs.